While the treatment of cancer was once considered impossible, great strides have been made during the past ten years in controlling the ravages of this often fatal disease. Several drugs which contribute to the increasing survival rate of patients diagnosed as having one of several types of cancer are now routinely used clinically. The most commonly employed antitumor drugs include methotrexate, doxorubicin, cytarabine and the vinca alkaloids such as vincristine. However, research continues to develop more effective compounds with improved efficacy and greater safety for subjects under treatment for cancer.
The search for chemical compounds with oncolytic activity has revealed a class of 2'-deoxy-2',2'-difluoronucleosides which exhibit excellent activity against a variety of tumors, both solid and non-solid types, as disclosed in EPO Application No. 85308547.0. These compounds, and their use as antiviral agents, are also disclosed in U.S. Pat. Nos. 4,526,988 and 4,692,434.
The present invention provides a new process for the inversion of 2-deoxy-2,2-difluororibose analogs to 2-deoxy-2,2-difluoroxylose analogs useful as intermediates for the synthesis of 3'-substituted-2',2'-difluoronucleosides for use as both oncolytic and antiviral agents. Novel intermediates used for this inversion are also provided.